"""Behaviour of the ventilation Recommendation Generator: detecting a dwelling
that lacks adequate mechanical ventilation and emitting a priced MEV
Recommendation. Like wall/roof/floor it does detection + pricing; unlike them it
is consumed by the Measure Dependency path, not the free candidate pool (it is a
forced dependency of fabric insulation — ADR-0016). See CONTEXT.md.
"""

from datatypes.epc.domain.epc_property_data import EpcPropertyData
from domain.modelling.generators.ventilation_recommendation import (
    recommend_ventilation,
)
from domain.modelling.product import Product
from domain.modelling.recommendation import Recommendation
from domain.modelling.simulation import VentilationOverlay
from repositories.product.product_repository import ProductRepository
from tests.domain.sap10_calculator.worksheet._elmhurst_worksheet_000490 import (
    build_epc,
)


class _StubProducts(ProductRepository):
    """In-memory ProductRepository returning a fixed per-unit ventilation cost."""

    def get(self, measure_type: str) -> Product:
        # unit_cost_per_m2 carries the catalogue row's fully-loaded total cost;
        # for ventilation that total is per installed unit.
        return Product(
            measure_type=measure_type, unit_cost_per_m2=450.0, contingency_rate=0.26
        )


def test_naturally_ventilated_dwelling_yields_a_mev_recommendation() -> None:
    # Arrange — 000490 lodges no mechanical ventilation kind.
    baseline: EpcPropertyData = build_epc()

    # Act
    recommendation: Recommendation | None = recommend_ventilation(
        baseline, _StubProducts()
    )

    # Assert — one MEV Option targeting the whole-dwelling ventilation system.
    assert recommendation is not None
    assert recommendation.surface == "Ventilation"
    assert len(recommendation.options) == 1
    option = recommendation.options[0]
    assert option.measure_type == "mechanical_ventilation"
    assert option.overlay.ventilation == VentilationOverlay(
        mechanical_ventilation_kind="EXTRACT_OR_PIV_OUTSIDE"
    )


def test_recommendation_prices_two_installed_units_with_contingency() -> None:
    # Arrange
    baseline: EpcPropertyData = build_epc()

    # Act
    recommendation: Recommendation | None = recommend_ventilation(
        baseline, _StubProducts()
    )

    # Assert — two MEV units at £450 each, carrying the product's contingency.
    assert recommendation is not None
    cost = recommendation.options[0].cost
    assert cost is not None
    assert abs(cost.total - 900.0) <= 1e-9
    assert abs(cost.contingency_rate - 0.26) <= 1e-9


def test_already_mechanically_ventilated_yields_no_recommendation() -> None:
    # Arrange — a dwelling that already lodges a mechanical ventilation kind
    # must not be told to install MEV (legacy has_ventilation guard).
    baseline: EpcPropertyData = build_epc()
    assert baseline.sap_ventilation is not None
    baseline.sap_ventilation.mechanical_ventilation_kind = "EXTRACT_OR_PIV_OUTSIDE"

    # Act
    recommendation: Recommendation | None = recommend_ventilation(
        baseline, _StubProducts()
    )

    # Assert
    assert recommendation is None


def test_dwelling_with_no_sap_ventilation_yields_a_recommendation() -> None:
    # Arrange — no SapVentilation at all counts as not mechanically ventilated.
    baseline: EpcPropertyData = build_epc()
    baseline.sap_ventilation = None

    # Act
    recommendation: Recommendation | None = recommend_ventilation(
        baseline, _StubProducts()
    )

    # Assert
    assert recommendation is not None